"He is now undergoing dialyses at the Mount Elizabeth Hospital," an official of the Bangabhaban presidential palace told PTI without elaboration.
However, 85-year old Rahman's son and ruling Awami League lawmaker Nazmul Ahsan Papan told PTI that he was suffering from severe lung infection.
"He is suffering from severe lung infection... doctors started removing waters from his lung as his condition stabilised a little and he is being treated at a cabin and is being given oxygen," Papan said.
Papan, also the president of the Bangladesh Cricket Board, rejected reports that the President was under life support system, sparking concerns about his condition.
Prime Minister Sheikh Hasina has urged the countrymen to pray for Rahman's recovery and a special prayer was offered in mosques after Magrib prayers and in other places of worship.
A Bangabhaban presidential palace official said, "Specialised physicians of the hospital were conducting Rahman's treatment after he was flown to Singapore on Sunday night by an Air Ambulance and he was admitted to the MountElizabethHospital on Monday morning.
Rahman was earlier admitted at CombinedMilitaryHospital at Dhaka cantonment on Saturday night as he complained of respiratory complications.
Officials familiar with the situation said Rahman was flown to Singapore after the doctors of both the countries jointly reviewed his fitness for the overseas travel.
Rahman, a veteran politician who celebrated his 85th birthday on Saturday, was installed as the ceremonial head of the state in 2009 after Prime Minister Sheikh Hasina's Awami League was elected in the landmark December 2008 general elections.
A lawyer by profession, Rahman was a close aide of Hasina's father and Bangladesh's founder Bangabandhu Sheikh Mujibur Rahman and is regarded as a key figure in consolidating the Awami League's unity at different times.
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